This invention relates to electrical connector assemblies for use in a pressurized environment and more particularly to corrosion-proof electrical connector assemblies that are pressure balanced.
Marine connectors in the prior art commonly employ an electrically insulating, non-hygroscopic liquid as a filler compound to protect the conductors, wired connections and contacts from corrosion. This requires a connector housing having a liquid-tight inner chamber in which the connector is immersed in the compound. It is usual to completely fill the chamber and to manually pressurize same in order to prevent intrusion of water which may otherwise occur under normal marine environmental pressure conditions.
A problem with the foregoing marine connector structure is to provide a housing that is sufficiently strong to withstand the pressure contained within the chamber without leaking. Although such pressure may be relatively low, on the order of ten pounds per square inch, connections joined to the housing must be liquid-tight in order to prevent loss of the insulating liquid compound. In the event that some liquid loss should occur, the resulting void in the chamber would permit deleterious pressures and stresses to be applied to the connector within the chamber. Furthermore, the void could permit the intrusion of water from the marine environment which would cause corrosion of the connector. In either event, mechanical and/or electrical failure would likely ensue.
One way of overcoming the foregoing problem is by providing a connector housing of more substantial construction having robust liquid-tight connections that are less prone to develop leaks. An obvious disadvantage with this solution to the problem, however, is the additional cost of manufacture to produce a stronger underwater connector assembly.
In order to reduce the requirement of increased structural integrity in the connector housing, known housings have been manufactured with weakened portions that are flexibly responsive to marine environmental pressures in order to atuomatically pressure balance the connector assembly. The application of envornmental pressures to flexible portions of the connector housing compresses the substantially incompressible liquid in the chamber of the housing which counterbalances the forces of the applied environmental pressure. In this arrangement, it is also required that the chamber be completely filled with the substantially incompressible liquid. Otherwise, a remaining void would allow excessive flexing of the weakened portions in the connector housing under pressure which could lead to damage or premature failure of the assembly. For this reason, an excess of insulating liquid is used to pressurize the housing in order to obviate the presence of a void.
Obvious disadvantages with a marine connector having pressure responsive flexible portions in the housing are higher manufacturing costs and problems concerning manufacture and assembly. A significant difficulty, also, is that if flexible portions of the housing are made readily responsive to pressure variations, the mechanical integrity of the connector housing may be reduced. Abusive handling would therefore result in an easily damaged housing.
An ancillary problem in the marine connectors of the prior art is found when such connectors are used under test conditions where operational parameters of marine environment are manipulated in the extreme. Of particular significance is temperature since the filling compound of the prior art connectors is commonly petroleum jelly or some other like hydrocarbon substance that has a large coefficient of thermal expansion. The problem of leaks developing as a result of pressurizing a connector housing is further aggravated by a substantially higher internal pressure which is generated by the filler compound when it is subjected to higher temperatures.